You know the green stuff at the tops of broccoli crowns...are those seeds?

Question

if not, what part of the plant do the seeds come from?

Answer 1

The stem is the unopened flowers so, if allowed to grow & be fertilized, it could set seed. The stem of broccoli is harvested before the flowers fully develop while it is tender enough to eat.  Here is a picture of broccoli allowed to grow and flower in order to have seed for next years crop.

http://home-and-garden.webshots.com/phot...

http://images.google.com/imgres?imgurl=h...

Answer 2

I think the green stuff are the flower buds.  So if allowed, they could flower and set seed.